I have an interesting experience with music. I'm not sure if it's synesthesia, but it seems to be similar.
I've been thinking about all of the weird things my mind does since I learned about AS and started to try and give them names.
When I listen to music I like, I can visualize wierd things. It's like a regular daydream I might have, but it's paced/timed to the music and it's much more vivid than usual. Almost like a real dream or something. I can get so caught up, I can forget where I am. It's probably not so unusual I guess. But, each song seems to have it's own "vision". I can generally remember the same exact sequence that occured when listening to the song earlier by hearing it again. However, this changes if I don't listen to the song for a while.
This is something I can control, so it's not like I just stop in my tracks when I hear a song I like or anything. But if I am alone and able to concentrate I could probably just spend a few hours doing it. I don't do it too often these days. It's sort of frustrating. I have all these nice images in my head, but I can't show anyone. I enjoy looking at them, but I have a hard time drawing them or writing them down. They never come out the same when I try to express them. They are too internalized and nobody speaks my "mind-talk" to be able to appreciate them... :/ lol